Individual interviews lasts anywhere from 5 minutes to 40 minutes (mine was 30 minutes). Then you wait for everyone else to finish their interviews before going on a group tour. Followed by lunch. You should be out by 12 ish.
If you get there early and your interviewer just happens to be there, you can get your interview over with early. I got there at 7:30. Went in and got it over with right away! Good luck!